The invention relates to an apparatus for stacking and aligning sheets fed individually into a storage container where they are collected in a pile. The storage container of the apparatus has a tray surface with a front stopping edge for aligning the sheets, and a retaining mechanism placed in the area of the front edges of the tray surface and located above the sheets to be stacked. The retaining mechanism has pivotable separating elements, is that when the stack of sheets is complete, these elements are temporarily swung into the path of the sheets still being fed into the storage container.
In an apparatus known from U.S. Pat. No. 5,007,797, sheets are fed into a storage container where they can be temporarily held back by a retaining mechanism with pivotable separating fingers in such a way that the stack of sheets already deposited can be stapled and/or removed. The separating fingers, which can be swung onto the top surface of the finished stack of sheets, are locked into position thereby limiting the holding capacity of the tray surface.
In another apparatus for stacking sheets (U.S. Pat. No. 5,014,977), the sheets are aligned at a front stopping edge by an aligning device in the form of an impeller which acts on the top surface of the stack of sheets. The impeller of this apparatus is mounted at the free end of a pivotably arranged carrier which is balanced out by means of a spring and counterweight thereby ensuring that the carrier can swing upwards as the stack of sheets grows in size.